1. Field of the Invention
This invention relates to the production of polyolefins and has particular reference to catalysts used therefor.
2. Description of the Prior Art
Heretofore, catalysts for the production of polyolefins were known which comprised transition metals such as titanium and vanadium carried on magnesium halide as disclosed, for example, in Japanese Patent Publication No. 39-12105. Another catalyst known in the art is described in Belgian Pat. No. 742,112 as comprising titanium tetrachloride carried on an anhydrous magnesium halide which has been activated by a ball mill. However, neither of the above prior art catalysts is satisfactory for the production of polyolefins in which a maximum of catalytic activity is required.
Accordingly, it is an object of the invention to provide a process for the polymerization or copolymerization of olefins with the use of a novel catalyst which exhibits a maximum of catalytic activity to permit use of reduced monomer partial pressure and of reduced reaction time, with a minimum of catalyst residues in the resulting polymer whereby the process can be carried out most economically without involving added steps for removal of residual catalysts.
It has now been found that the process of the invention, wherein catalyst residues in the product polymer are held to an absolute minimum will also provide marked improvements in respect of "fish-eye", "tear", "transparency", etc. of the end products.